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[SelectionDAGBuilder] Simplify visitShift. NFC 

This code was detecting whether the value returned by getShiftAmountTy
can represent all shift amounts. If not, it would use MVT::i32 as a
placeholder. getShiftAmountTy was updated last year to return i32
if the type returned by the target couldn't represent all values.

This means the MVT::i32 case here is dead and can the logic can
be simplified.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D120164
This commit is contained in:
Craig Topper 2022-02-19 12:03:28 -08:00
parent 55e0b388d0
commit 24bfa24355
1 changed files with 5 additions and 19 deletions
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24
llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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@ -3150,26 +3150,12 @@ void SelectionDAGBuilder::visitShift(const User &I, unsigned Opcode) {
EVT ShiftTy = DAG.getTargetLoweringInfo().getShiftAmountTy(
Op1.getValueType(), DAG.getDataLayout());
// Coerce the shift amount to the right type if we can.
// Coerce the shift amount to the right type if we can. This exposes the
// truncate or zext to optimization early.
if (!I.getType()->isVectorTy() && Op2.getValueType() != ShiftTy) {
unsigned ShiftSize = ShiftTy.getSizeInBits();
unsigned Op2Size = Op2.getValueSizeInBits();
SDLoc DL = getCurSDLoc();
// If the operand is smaller than the shift count type, promote it.
if (ShiftSize > Op2Size)
Op2 = DAG.getNode(ISD::ZERO_EXTEND, DL, ShiftTy, Op2);
// If the operand is larger than the shift count type but the shift
// count type has enough bits to represent any shift value, truncate
// it now. This is a common case and it exposes the truncate to
// optimization early.
else if (ShiftSize >= Log2_32_Ceil(Op1.getValueSizeInBits()))
Op2 = DAG.getNode(ISD::TRUNCATE, DL, ShiftTy, Op2);
// Otherwise we'll need to temporarily settle for some other convenient
// type. Type legalization will make adjustments once the shiftee is split.
else
Op2 = DAG.getZExtOrTrunc(Op2, DL, MVT::i32);
assert(ShiftTy.getSizeInBits() >= Log2_32_Ceil(Op1.getValueSizeInBits()) &&
"Unexpected shift type");
Op2 = DAG.getZExtOrTrunc(Op2, getCurSDLoc(), ShiftTy);
}
bool nuw = false;